Moorings on the Piscatiqua River?
We had a mooring in Kittery Yacht Yard last year. It is behind the Navy shipyard and an awesome location, great shelter, no wake issues and fifteen minutes to the ocean BUT it was, as I recollect, about $3200 for the season.
We live in Portsmouth (which is a great little town) but we have moved our boat up to Georgetown Maine because the sailing is so much more interesting. Sailing to the Shoals and back can get old after a while....
I would look at Portland or beyond. There are some delightful spots and a mooring there makes for a pretty cheap weekend 'waterfront' property.
Graham and Janaki